Author:

Keywords:

review, esoscopic modelling, molecular modelling, chain conformation, morphology, crystallisation, polyolefins, homogeneous ionic polymerization, monte-carlo simulations, elastomeric poly(propylene), stereoblock homopolymers, metallocene catalysts, olefin polymerization, multistate mechanism, ziegler-catalysts, polypropylene, polymers, Science & Technology, Technology, Materials Science, Textiles, Materials Science, HOMOGENEOUS IONIC POLYMERIZATION, MONTE-CARLO SIMULATIONS, ELASTOMERIC POLY(PROPYLENE), STEREOBLOCK HOMOPOLYMERS, METALLOCENE CATALYSTS, OLEFIN POLYMERIZATION, MULTISTATE MECHANISM, ZIEGLER-CATALYSTS, POLYPROPYLENE, POLYMERS, Polymers

Abstract:

A review describing the latest advances in the mesoscopic and molecular modelling of polyolefins is presented. Mesoscopic investigation into the effects of sequence length and sequence length distribution on the reinforcement of stereoblock-stereoregular polyolefins has been performed. These polymers consist of alternating atactic sequences, which are amorphous and act as elastomeric chains, and isotactic sequences which, if long enough, will crystallise, and act as physical reinforcing cross-links. According to simulated morphology, the degrees of crystallinity of the different samples have been predicted. Mechanical properties such as Young's modulus at small extensions are also predicted in terms of the block size of the alternating isotactic and atactic sequences. Molecular simulation investigation into the influence of the chain microstructure on the conformational behaviour of these polymers has been detailed. Characteristic ratios, calculated on the basis of the rotational isomeric state model, have indicated the increased extension of the polymer backbone with the increase in the side chain length. The lower characteristic ratio calculated for octene polymers may explain the experimental observation that polyoctene has a lower melting point than other polyolefins. Probability distribution surfaces constructed by the integration of the molecular dynamics trajectories indicated an increase in the probability of g(+/-)t joint states on the expense of g(+/-)g(+/-) pairs with the increase in the side chain length.